Deepsea microbes in very slow lane
Ancient, plodding creatures may have last had new food when dinosaurs roamed the Earth
LOS ANGELES — Had enough of life in the fast lane and looking to take it down a notch or two? You might seek guidance from a colony of deepsea microbes harvested from the barren depths of the Pacific Ocean that are progressing so slowly, they almost appear to be dead.
Just how plodding are these ancient creatures, who are buried about 30 metres deep in the seabed? Some of them haven’t received any new food for 86 million years, when dinosaurs still walked the Earth. And they are using up oxygen at rates only one- 10,000th that of their counterparts on the surface of the ocean floor.
“What they’re doing, they’re doing so slow that from our time perspective, it just looks like suspended animation,” said biologist Hans Roy, who reported on the creatures in the current edition of the journal Science.
The single- cell organisms live in such extreme conditions that they could help astrobiologists search for evidence of life on less hospitable planets, scientists said.
The ocean floor contains a wealth of microbial life — some experts estimate that nearly 90 per cent of microorganisms on the planet live beneath the seabed.
“There’s an abundant biosphere below the surface skin where we live ... and yet most of what is down there is living at a pace and in a mode that we don’t have represented in the world around us,” said Tori Hoehler, a biogeochemist at the NASA Ames Research Center’s exobiology branch near San Jose, who was not involved in the study. “Most of life lives in a mode we don’t understand at all.”
Chief among them are the slow- living microbes, which were discovered several years ago, said Roy, who is based at Aarhus University in Denmark.
Roy was part of a team of scientists that set out on a ship in 2009 to sample spots around the Galápagos Islands along the equator and up toward an area near Hawaii in the northern Pacific, where ocean currents block nutrient- rich sediments from falling to the ocean floor. That keeps microbes at the bottom from receiving fresh food.
The researchers drilled deep into the ocean floor and extracted a core sample that was about 100 feet long. Among other things, they examined the oxygen levels in the successive layers of thick, greyish mud using needlelike sensors.
When the researchers measured the rate of oxygen respiration, they found that there were still microbes eking out a meagre existence in the deepest layers.
The age of these microbes is unclear. Estimates range from a few centuries to many millions of years, researchers said.
Understanding how they survive could provide pointers for scientists looking for life on other planets, such as Mars. In the search for extraterrestrial life, Hoehler said, such slow-life communities below the bottom of the sea “may be a much better point of reference for us than what’s up here.”